The invention is related to ad-hoc established device networks, which comprise a central controller and a set of terminal devices. In particular, the invention is related to a method for optimizing data traffic in an ad-hoc established device network, to a central controller for controlling a set of terminal devices in an ad-hoc established device network, and to a gateway device for connecting the device network with an external network.
For a variety of home multimedia applications and business applications, it is important to establish networks, preferably wireless networks, for exchanging data and messages between different devices that are part of the network. In a typical business application scenario, a mobile terminal gets services over a fixed corporate or public infrastructure. In an exemplary home application scenario, a low-cost and flexible networking is supported to interconnect wireless digital consumer devices.
The ETSI Project BRAN (Broadband Radio Access Networks) has defined the standard HIPERLAN (High Performance Radio Local Area Network), which provides high-speed multimedia communications between different broadband core networks and mobile terminals. HIPERLAN/2 provides a flexible platform for a variety of business and home applications that can support a set of bit rates up to 54 Mbit/s. The HIPERLAN/2 standard is an example how data can be transmitted between different devices in a wireless network. The invention is not limited to wireless networks according to the HIPERLAN/2 standard, though. The invention is not limited to wireless networks. It can also be applied in wired networks.
A typical device network comprises several devices, with one of the devices acting as a central controller that controls the other devices which act as terminal devices. When different devices are brought within reach of each other, they start exchanging messages and establish a so-called ad-hoc network. The first device on the ad-hoc network is taking the control functionality of the network. In case more than one controller-capable device exist in the network, any of these devices could become the first device on the network and thus the network's central controller.
In the so-called centralized mode, a data packet that is sent from a first terminal device to a second terminal device has to be routed via the central controller. The data stream from the first terminal device to the second terminal device is “reflected” by the central controller. The reflected data streams cause a lot of extra data traffic; they increase the network load significantly.
Most device networks comprise a gateway device which provides a connection between the ad-hoc established device network and external networks, e.g. the Internet. Outbound data traffic that is sent from a terminal device to the gateway has to be routed via the central controller, and thus, a reflected data stream is generated. Inbound data traffic arriving at the gateway also has to be routed via the central controller before it is distributed to the respective terminal device. Again, reflected data streams are generated.